Air bags and other devices for helping to protect a vehicle occupant during a vehicle event such as a crash, roll-over, etc., are known. To detect such a vehicle event, one or more event sensors are mounted to the vehicle and provide signals indicative of sensed vehicle event conditions for which actuation of the protection device may be desired. The event sensors are connected to an electronic controller that evaluates the event sensor signals using appropriate event metrics to monitor and determine if a particular event is occurring, e.g., a vehicle crash condition. Upon determining the occurrence of a particular type of vehicle event by the electronic controller, the vehicle occupant protection devices, e.g., air bags, inflatable side curtains, etc., are actuated.
Pedestrian protection systems have been proposed to aid in reducing pedestrian injury when the pedestrian is struck by a moving vehicle (a “vehicle/pedestrian impact”). Some proposed pedestrian protection systems include a sensor mounted in the vehicle bumper. If the sensor detects an impact with a pedestrian, an actuatable device is actuated to mitigate the impact effect. Such actuatable devices include, for example, actuators to raise the trailing end of the hood. Actuatable forward mounted air bags have also been proposed to mitigate vehicle/pedestrian impact effects.
One known approach for detecting impacts with pedestrians involves a closed, gas-filled, compressible tube disposed along the length of the vehicle's front bumper. In the event of an impact, the pressure of the gas in the tube will spike because of compression of the tube. Pressure sensors at one or both ends of the tube detect the spike in pressure, and the controller responds by deploying the pedestrian protective device.
A variety of pedestrian impact sensors and vehicle crash sensors may all be arrayed in the front end of the vehicle. Such sensor systems typically require multiple wiring harnesses and fastening systems that add weight and complexity on the vehicle.
It would be beneficial if the front impact sensing systems could be simplified while also improving the performance of the sensors.